Levels having a bubble are sometimes difficult to read and can be broken when dropped. The bubble type level is not suitable for indicating precise amounts of deviation from the vertical or horizontal.
Barger U.S. Pat. No. 1,618,262, Barnett U.S. Pat. No. 1,700,278, and Iverson U.S. Pat. No. 1,732,335 disclose a pointer-type level wherein a transverse rotary shaft is mounted in two axially spaced bearings located at the ends of the shaft. This arrangement has problems with maintaining the shaft and pointers in alignment.
Bertram U.S. Pat. No. 1,705,889 and Morrison U.S. Pat. No. 1,844,590 disclose only a single pointer and single scale along one side of the frame.